1. Field of the Invention
The present invention relates to an optical pickup for irradiating light onto a recording medium to record information in the recording medium and to read information therefrom, and more particularly, an optical pickup having a tilt mechanism to adjust an optical axis of an incident light beam to compensate for tilting of a recording medium such as an optical disk.
2. Description of the Related Art
In general, an optical recording/reproducing apparatus such as a disk player, for recording information in a recording medium such as an optical disk and reproducing information therefrom, comprises an optical pickup for reading information from light that is irradiated onto the optical disk and then reflected therefrom. In a conventional optical pickup, as shown in FIGS. 1 and 2, a base plate 21 is installed on a fixed base 20, and a bobbin 23 in which an objective lens 19 is mounted is movably supported by wires 28 in a fixed block 22 situated on the base plate 21. Also, a focusing coil 26 for controlling the focus of a spot of light formed on an optical disk 30, and a tracking coil 27 for laterally moving the objective lens 19 such that the spot of light formed on the optical disk 30 accurately tracks the tracks (not shown) of the optical disk 30, are installed in the bobbin 23. The bobbin 23 moves by an electromagnetic force due to interaction between a current flowing through the focusing coil 26 and the tracking coil 27, and the magnetic field produced by a magnet 25 and a yoke 24 installed in the base plate 21. A reflecting mirror 18 for changing an optical path, and a fixed optical system 10 for irradiating light from the reflecting mirror 18 to the optical disk 30 and receiving the light reflected by the optical disk 30 are placed below the objective lens 19. As shown in FIG. 1, the fixed optical system 10 includes a light source 11, a beam splitter 13, a collimating lens 14, a detecting lens 15 and a photodetector 12. Also, each semispherical base of the fixed base 20 and the base plate 21 contact each other and are coupled by a plurality of adjusting screws 41, 42 and 43, such that the tilt of the base plate 21 with respect to the fixed base 20 can be adjusted by tightening the plurality of adjusting screws 41, 42 and 43. This structure is suitable for correcting an error through the controlling of the fightness of the adjusting screws 41, 42 and 43 during the assembly process in the case when an optical axis C of light incident through the objective lens 19 perpendicularly onto the optical disk 30 is tilted, that is, when the light is obliquely incident, not perpendicularly, onto the optical disk 30. Reference numeral 50 represents a controller for controlling the focusing and tracking operations, and reference S represents a compression spring.
However, the optical disk 30 may be tilted due to vibration during the recording/reproducing operation as well as during the assembly process, and the optical disk 30 may not be level due to minute deformations of the optical disk 30 itself. However, the conventional optical disk can not cope with such a problem. In other words, even when the tilt of the optical axis C during the assembly can be corrected, the tilting of the optical axis C during the recording/reproducing operation after the assembly process cannot be corrected. As a result, the intensity of light formed on the optical disk is not strong enough for the recording operation and a playback signal is deteriorated, so that it is difficult to accurately reproduce the information.